Most people at some point in a relationship will meet someone who looks like they would be a "better" partner. However, marriage includes the expectation of primariness: the commitment of both partners to keeping each other the most important person in their life. Usually couples agree that primariness will include the expectation in which partners promise to have sexual relations only with each other (Reiss, 1986; Pittman, 1980).

Rather than being upset when you see someone who looks more appropriate to you, it is usually a sign that you need to pay more attention to your current relationship. As well, it is likely you or your partner is at a transition or change phase in your relationship. For example, birth of a child, a new job, children launched, or return to school. Affairs are most likely to happen during these phases in a couple's life cycle (Rees, 1985).

Taboos against extramarital sex are widespread throughout the world’s cultures. More than any other part of the world, about 70 percent of North Americans believe that extramarital sex is "always wrong" and only 4 percent felt it is "never wrong" (Davis, 1980; Macklin, 1987). While a large majority of people publicly disapprove of extramarital sex, in practice it is somewhat different

Gathering statistics on affairs is very difficult. The results vary due to the type of group being studied, the reporting method, and because we know people are lying, even when the research is anonymous. The percentage of those who say they have had affairs ranges from 25% to 75% of all males and 15% to 60% of all women

So what have researchers learned? Back in 1953 Alfred Kinsey learned that 26 percent of wives and 50 percent of husbands said they had had a least one affair by the time they were 40 years old (Kinsey, Pomeroy, and Martin, 1953). Humphrey and Strong in 1976 found that 46% of all couples coming for couple therapy identified the problem as one or both partner’s extramarital affair. In 1990, Reinisch reviewed a number of studies to find affair rates of 37% for men and 29% for women. Janus and Janus (1993) found very similar figures with 35% of married men and 26% of married women reporting at least one extramarital sexual encounter. Spring (1997) says affairs affect one of every 2.7 couples - in-other-words 37% of couples. Psychologist Layton-Tholl, (1998) says the current acceptable statistic is roughly half of all men and women get involved in extramarital affairs. Vaughn (1998) has an even more startling analysis of the data. She approximates that 80% of marriages will be affected by one partner who has an affair. She basis this on an estimate that 60% of men and 40% of women who are married will have an affair. She estimates that 20% of the women will have affairs with unmarried men not included in the 60%

While the media, society, family, and friends focus on the sexual aspects of an affair - research repeatedly shows that affairs are seldom about sex. In fact, only about 10 percent of the time according to Layton-Tholl (1998). What we do know is that affairs are loaded with romance, morality, and intense emotions. And they are also about pain, fear, the desire to feel alive, and betrayal. Most people enter marriage believing they would never have an affair. As the numbers indicate above, many people have one or more affairs.